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POWER
The power consumption of an add-on video card can be estimated by comparing
the total system power draw with and without the card installed on our test system. Our results
were derived thus:
1. Power consumption of the graphics card at idle - When CPUBurn is run on a system, the video card is not stressed at all, and stays in idle mode. This is true whether the video card is integrated or an add-on PCIe 16X device. Hence, when the system power under CPUBurn with just the integrated graphics is subtracted from the system power under CPUBurn with the add-on card, we obtain the increase in idle power of the add-on card. (The actual idle power of the add-on card cannot be derived, because the integrated graphics does draw some power — we'd guess no more than a watt or two.)
2. Power consumption of the graphics card under load - The power draw
of the system is measured with the add-on video card, with CPUBurn and ATITool
running simultaneously. Then the power of the baseline system (with integrated
graphics) running just CPUBurn is subtracted. The difference is the load power
of the add-on card. (If you want to nitpick, the 1~2W power of the integrated
graphics at idle should be added to this number.) Any load on the CPU from ATITool
should not skew the results, since the CPU was running at full load in both
system. Recently we have been using the Furmark utility in place of ATITool
as it has been found to increase power consumption more than ATITool. As many
of our previous results were obtained using ATITool, we have opted to test with
both programs to keep older comparisons more accurate.
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Power Consumption Comparison (DC)
|
|
Card
|
Est. Idle Power
|
Est. Load Power (ATITool)
|
Est. Load Power (FurMark)
|
|
ATI HD 4670
|
3W
|
38W
|
40W
|
|
ATI HD 3850
|
11W
|
55W
|
N/A
|
|
Asus EN9600GT Silent
|
26W
|
65W
|
N/A
|
|
Palit HD 3870
|
17W
|
72W
|
N/A
|
|
ATI HD 4830
|
18W
|
80W
|
87W
|
|
Diamond HD 4850
|
50W
|
101W
|
N/A
|
|
Asus ENGTX260
|
35W
|
122W
|
N/A
|
By our measurements the HD 4830 used a modest amount of power at idle —
18W, which is closer to the HD
3870 than the HD 4850. The HD 4850 seemed to have had
malfunctioning power management when it was tested — we're not sure if
this is still the case. Load power was 11% higher than the HD 3870, but 21%
lower than the HD 4850. Unless the HD 4830's efficiency is extremely low or
high, its 3D performance should lay somewhere in between these two cards.
PowerPlay, ATI's power management technology seemed to be working on the HD
4830 as the idle power measurement was fairly low. Also, according to GPU-Z,
when idle and during video playback the core and memory speeds stayed underclocked
at 160/250Mhz. Only when ATITool or FurMark was running did the clock speeds
rise to its maximum 575/900Mhz.
Video Playback
The HD 4830 handled our video playback testbed with ease. CPU usage during
playback failry low except for our more demanding VC-1 clips. The H.264 Rush
Hour 3 trailer had a trivial effect on system resources.
|
Video Playback Results: HD 4830
|
|
Video Clip
|
Mean CPU Usage
|
Peak CPU Usage
|
AC Power
|
|
Rush Hour
|
4%
|
9%
|
~123W
|
|
Coral Reef
|
31%
|
41%
|
~134W
|
|
Flight Sim.
|
57%
|
79%
|
~153W
|
|
Drag Race
|
66%
|
83%
|
~160W
|
In terms of CPU usage, video playback was very similar to the previous Radeons.
Power consumption during video playback were at levels in-between the HD 4850
and HD 3870, just as they were during idle and full load.
|
Video Playback Comparison
|
|
Video Clip
|
Palit HD 3870
|
ATI HD 4830
|
Diamond HD 4850
|
|
Mean
CPU
|
AC
Power
|
Mean
CPU
|
AC
Power
|
Mean
CPU
|
AC
Power
|
|
Rush Hour
|
3%
|
~105W
|
4%
|
~108W
|
3%
|
~136W
|
|
Coral Reef
|
27%
|
~118W
|
31%
|
~134W
|
28%
|
~151W
|
|
Flight Sim.
|
50%
|
~130W
|
57%
|
~153W
|
55%
|
~168W
|
|
Drag Race
|
N/A
|
66%
|
~160W
|
73%
|
~176W
|
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